Underreamer



Feb. 129 i924,

P. J. FGRRET UNDERREAMER Filed Jan. 24. 1922 Patented Feb. l2, 122%. i

i arrt PROSIER J. FORREST, OF ALAMEDA, CALIFORNA, SSIGNDR 0F ONE-HALF TO NETTL FORBEST, OF SAN FRANCISCO, GLFORNQA.

UNDERE'EAMER.

Application filed JanuaryZ/L, 1922. Serial No. 531,461.

To all whom t may concern: v

Be it known that l, Pizosrnn J. Fonnnsr, a citizen of the United States, and resident of the city and county of Alameda, State of California, have invented new and useful improvements in Underreameisof which the following is a specification.

My invention has for its object a reliable and efficient underreamei1 construction whereby the reamer blades are held together in a xed jointed relation.

A. further object is to secure an underreamer wherein equal duty is at all times imposed upon each of the blades. vAnother obj ect is to provide an underreamer whereby the cutting blades are forced into an extended position by a coil spring, or when they are retracted by being drawn. against a well casing, they are collapsed to a nonworking position and are there held during the withdrawal of the tool. V

Other objects will appear from the drawiii s and specifica-tions which follow:

iig. 1 is a cross section through the underreamer head showing in full lines the two reamer blades in their extended position as when adapted to drill a hole suitable for inserting or forcing down the well casing, and by dotted lines the said blades are shown collapsed.

Fig. 2 is a perspective detail of one of the reamer blades.

Fig. 3 is a reduced side view of the complete reamer of Fig. 1.

Throughout the drawings similar numerals refer to identical parts.

The well to be drilled is indicated by the numeral 1 within which it is desired to drive the casing 2, 2. The stock or head piece of the reamer is indicated by the numeral 3 and it is understood that this head is to be attached to suitable well rods or fixtures of any conventional form as by the taper screw thread at l and by which the head is operated in reciprocating movement when drilling the hole 1.

In Fig. 1 the well casing is shown as extending down to the line 5 and below this line is the working range of the reamer shown in the ligure.. After the hole 1 has been suitably' drilled for a sufficient depth the casing 2 is then driven further down and the reamer drilling continued in this manner always beyond. the end of the said casing. At 6, 7, are shown the reamer blades the blades 6, 7 downward during the cutting;-

stroke. ln the full line position shown tha` blades 6, 7 are held against the head 3 at the shoulders 8, 9, by the action of the coil spring 10, normally in compression, and forcing the nut 11 and therefore the rod 12 in an upward direction. The said rod 12 carries on its lower end an enlarged portion 13 through which is a key-way and mounted therein a key 14 which key also passes through the Shanks of the blades 6, 7. This key is normally inserted from the dotted position 15 throughl a key]k slot in the side of the head 3 and has a working range within the slots 16, 17, respectively, corresponding with the movement of the cutter blades from the full positions 6, 7, to the dotted positions 18, 19, respectively, as will be more fully explained below.

The blades 6 and 7 are symmetrical with respect to each other, each of them have a convex projection 20 and a concavity 21. The corresponding projection of the blade 7 is adapted to hinge within the socket 21 and the blade 7 carries a corresponding socket in which the projection 20 of the blade 6 is adapted to likewise hinge. The axis of this hinge movement passes through the center of the ball recess 22, in which is mounted the ball end 23 on the rod 12. lt will thus be seen that the blades 6 and 7 and the ball end 23 are in hinge relation so that the two blades move inward and outward about an axis passing through the center of said ball and the projection and concavities, whereby their cutting edges 24, 25, respectively, are at all timesy presented for equal cutting, thus insuring longer life and a more perfect hole.

If it is desired to withdraw the reamer from the hole, the head 3 is raised from the hole by the drill mechanism at the top, not shown but well known, until the shoulders 26, 27, of the blades 6, 7, contact with the end 5 of the casing 2, at which time the said blades are forced downward, with respect to the head 3, further compressing the spring 10 until they occu y the relative dotted positions. During t is movement the blades have pivoted inward about the ball 23 and hinge axis mentioned above and have collapsed into the dotted positions 18,

19, so that the entire reamer structure is easily withdrawn through the casing 2.

`When the reamer isagain let down into the hole the blades contact with the bottom of the hole Vwhich forces the taper portion 30 (see Fig. 2) upward within thehead 3 at which time the blades are forced to pivot outward about the hinge axis and eX- tend into their full line position 6, 7. At 28 is a hole preferably smaller than the key 14 for the purpose of removing the key by forcing it out as shown in the dotted position 15 when it is desired to take the reamer to pieces.l t is to `be understood that the shoulders 26, 27, on the blades G, 7, do not go entirely around the reamer blades but are 'preferably of elliptical or crescent shape having their greatest width in the cross section position shown in Fig.

.1, and disappearing into the body of the material as the extremities of the pivotal axis is approached so that in the ldotted positions 18, 19, as the blades are collapsed,y

the said shoulders collapse entirely within the circle of the well casing 2. It will be noted that the ball 23 inthe spherical socket 22 retains the blades 6, 7 in position independent of the key 14 and at all times retains their alignment.

I claim:

1. In an underreamer, a reamer head and a. plurality of cutting blades joined in pivotal relation intermediate their ends, each blade having a lower cutting end and an upper end adapted to sheath inea recess in the head to hold the cutting ends expanded in their cutting position, a rod passing through the head and having a ball shaped end over which the said blades are adapted to pivot, a spring associated with said rod whereby the blades are normally retracted with their upper ends within said recess, shoulders on the blades adapted to contact with a well casing when the head is drawn upward thereby actuating the rod and spring to release the upper ends of the blades from the recess when the said cutting ends collapse inwards as the blades pivot over the said rod end, and a key which is passed through the blades and the rod, and engaging within the head.

2. An underreamer as set forth in -claim 1 wherein said head is provided with means constructed and adapted to secure said head to a drill rod.

3. An underreamer as set forth in claim lwherein the blades are two in number and each is provided with a cylindrical seat and cylindrical pintle, the pintle of one fitting within the seat of the other blade, a

spherical bearing between the pintles in the blades adapted to inclose said ball.

4. An underreamer as set forth in claim 1 wherein the blades are two in number and each is provided with a cylindrical seat and cylindrical pintle,` the pintle of one fitting withink the seat of the other blade and ,between the pintles a spherical bearing in the blades adapted to inclose said ball, and wherein said head is provided with means constructed and adapted to secure said head to a drill rod.

PROSPER J. FORREST. 

